THE OPALINID CILIATE INFUSORIANS. 445 



Metcalf (1918, h) gives a brief abstract of a lecture before the Bio- 

 logical Society of Washington. The lecture described, and the ab- 

 stract made reference to, the series of mitotic conditions observed in 

 the " resting " nuclei of different species of Opalinids, and the origin 

 of the binucleated condition in the Ciliata was discussed. A classi- 

 fication of the Ciliata was given, as follows : 



Ciliata. 



Protociliata. 

 Opalinidae. 



Protoopalina. 

 OpaZina. 

 Euciliata. 



Pinto (1918) describes and adequately figures the new species 

 " Opalhm " {Zellenella) hrasiliensis from Leptodactylus ocellatus. 



Cordero (1919) reports Opalinids, which he identifies with Zelleri- 

 ella antilliensis. from Leptodactylus ocellatus from La Plata, Lepto- 

 dactylus prognatJms from Tacuarembo, Uruguay, and from Bufo 

 arenai^'m from Montevideo. [It seems possible that more detailed 

 study of the parasites in these three species would show them not to 

 be of the species antilliensis.'] Twelve out of fifteen specimens of 

 Bufo arenarum were infected. Only one infected individual each of 

 Leptodactylus ocellatus and of L. prognathus were found. Six speci- 

 mens of Hyla ^^ raddiana^^ [pulchella'] were without Opalinids. 

 Nyctotherus {cordiformis'i) was ass'ociated with Zellenella in Bufo 

 arenarum and Leptodactylus ocellatus. Zelleriella antilliensis., or a 

 closely related binucleated species, was found in Pseudis mantidac- 

 tyla., Paludicola hihronii, Limnomedusa macroglossa and Bufo 

 d'^orhignyi {^^ orhignyi"). [The identification of these forms with 

 the species antilliensis should be reviewed.] 



Claoue (1919) reports again Kunstler's observations and views as 

 to the protoplasmic structure in Cepedea dimidiata. 



Metcalf (1920,a) discusses the classification of the Opalinidae, 

 summarizing it as in the present paper (see p. 271). 



Metcalf (1920,&) discusses the occurrence of Leptodactylidae in- 

 fected with Zelleriella in both South America and Australia and em- 

 phasizes the conclusiveness of the evidence from the distribution of 

 the hosts with their parasites that South America and Australia 

 were once connected by land. He discusses also, from similar data 

 of distribution of Anura and their Opalinid parasites, the early sepa- 

 ration of Patagonia from tropical America and their later union, and 

 urges the use of such study of double or multiple series of data from 

 hosts and their parasites in investigating problems connected with 

 geographical distribution. 



